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The flower is the main organ that produces essential oils in many plants. The yield of raw flowers and the number of secretory epidermal cells are the main factors for essential oil production. The cultivated rose species "Pingyin 1" in China was used to study the effect of RrANT1 on floral organ development. Eighteen AP2 transcription factors with dual AP2 domains were identified from Rosa rugosa genome. RrANT1 belonged to euANT . The subcellular localization results showed that RrANT1 protein is localized in the nucleus. The relative expression level of RrANT1 in the receptacle is higher than that in petals in the developmental stages, and both decreased from the initial phase to senescence. Compared with the RrANT1 expression level in petals in the blooming stage, RrANT1 expression level was significant in petals (~48.8) and highest in the receptacle (~102.5) in the large bud stage. It was only highly expressed in the receptacle (~39.4) in the blooming period. RrANT1 overexpression significantly increased petunia flower and leaf sizes (~1.2), as well as flower fresh weight (~30%). The total number of epidermis cells in the petals of overexpressing plants significantly increased (>40%). This study concluded that RrANT1 overexpression can increase the size and weight of flowers by promoting cell proliferation, providing a basis for creating new rose germplasm to increase rose and essential oil yield.

Floral organ size, especially the size of the corolla, plays an important role in plant reproduction by facilitating pollination efficiency. Previous studies have outlined a hypothesized organ size pathway. However, the expression and function of many of the genes in the pathway have only been investigated in model diploid species; therefore, it is unknown how these genes interact in polyploid species. Although correlations between ploidy and cell size have been shown in many systems, it is unclear whether there is a difference in cell size between naturally occurring and synthetic polyploids. To address these questions comparing floral organ size and cell size across ploidy, we use natural and synthetic polyploids of Nicotiana tabacum (Solanaceae) as well as their known diploid progenitors. We employ a comparative transcriptomics approach to perform analyses of differential gene expression, focusing on candidate genes that may be involved in floral organ size, both across developmental stages and across accessions. We see differential expression of several known floral organ candidate genes including ARF2 , BIG BROTHER , and GASA/GAST1 . Results from linear models show that ploidy, cell width, and cell number positively influence corolla tube circumference; however, the effect of cell width varies by ploidy, and diploids have a significantly steeper slope than both natural and synthetic polyploids. These results demonstrate that polyploids have wider cells and that polyploidy significantly increases corolla tube circumference.

Divergence in reproductive traits between closely related species that co-occur contributes to speciation by reducing interspecific gene flow. In flowering plants, greater floral divergence in sympatry than allopatry may reflect reproductive character displacement (RCD) by means of divergent pollinator-mediated selection or mating system evolution. However, environmental filtering (EF) would prevail for floral traits under stronger selection by abiotic factors than pollination, and lead to sympatric taxa being more phenotypically similar. We determine whether floral UV pigmentation and size show signatures of RCD or EF using a biogeographically informed sister taxa comparison. We determine whether 35 sister pairs in the Potentilleae tribe (Rosaceae) are allopatric or sympatric and confirm that sympatric sisters experience more similar bioclimatic conditions, an assumption of the EF hypothesis. We test whether interspecific differences are greater in allopatry or sympatry while accounting for divergence time. For UV pigmentation, sympatric sisters are more phenotypically similar than allopatric ones. For flower size, sympatric sisters show increased divergence with time since speciation but allopatric ones do not. We conclude that floral UV pigmentation shows a signature of EF, whereas flower size shows a signature of RCD. Discordant results between the traits suggest that the dominant selective agent differs between them., (© 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.)

Key Message: Expression differences underlie the functional differences between two related transcription factors: AINTEGUMENTA and AINTEGUMENTA-LIKE6. Ectopic expression of AINTEGUMENTA-LIKE6 at high levels alters floral organ initiation, growth and identity specification. AINTEGUMENTA (ANT) and AINTEGUMENTA-LIKE6 (AIL6) encode related transcription factors with partially overlapping roles in floral organ development in Arabidopsis thaliana. To investigate whether the functional differences between ANT and AIL6 are a consequence of differences in gene expression and/or protein activity, we made transgenic plants in which a genomic copy of AIL6 was expressed under the control of the ANT promoter. ANT:gAIL6 can rescue the floral organ size defects of ant mutants when AIL6 is expressed at similar levels as ANT in wild type. Thus, the functional differences between ANT and AIL6 result primarily from gene expression differences. However, lines that express AIL6 at higher levels display additional phenotypes that include reduced numbers of floral organs and the production of mosaic floral organs. These phenotypes were also observed in two different inducible AIL6 transgenic lines but not in 35S:ANT, suggesting that AIL6 protein may have activities distinct from ANT, although the in vivo relevance of such differences is not clear. Similar to 35S:ANT plants, overexpression of AIL6 in the inducible lines also results in the production of larger flowers. The distinct phenotypes resulting from AIL6 misexpression in the transgenic lines described here and those previously characterized appear to result from different levels and patterns of AIL6 expression.

Background: How floral traits and community composition influence plant specialization is poorly understood and the existing evidence is restricted to regions where plant diversity is low. Here, we assessed whether plant specialization varied among four species-rich subalpine/alpine communities on the Yulong Mountain, SW China (elevation from 2725 to 3910 m). We analyzed two factors (floral traits and pollen vector community composition: richness and density) to determine the degree of plant specialization across 101 plant species in all four communities. Floral visitors were collected and pollen load analyses were conducted to identify and define pollen vectors. Plant specialization of each species was described by using both pollen vector diversity (Shannon's diversity index) and plant selectiveness (d' index), which reflected how selective a given species was relative to available pollen vectors., Results: Pollen vector diversity tended to be higher in communities at lower elevations, while plant selectiveness was significantly lower in a community with the highest proportion of unspecialized flowers (open flowers and clusters of flowers in open inflorescences). In particular, we found that plant species with large and unspecialized flowers attracted a greater diversity of pollen vectors and showed higher selectiveness in their use of pollen vectors. Plant species with large floral displays and high flower abundance were more selective in their exploitation of pollen vectors. Moreover, there was a negative relationship between plant selectiveness and pollen vector density., Conclusions: These findings suggest that flower shape and flower size can increase pollen vector diversity but they also increased plant selectiveness. This indicated that those floral traits that were more attractive to insects increased the diversity of pollen vectors to plants while decreasing overlap among co-blooming plant species for the same pollen vectors. Furthermore, floral traits had a more important impact on the diversity of pollen vectors than the composition of anthophilous insect communities. Plant selectiveness of pollen vectors was strongly influenced by both floral traits and insect community composition. These findings provide a basis for a better understanding of how floral traits and community context shape interactions between flowers and their pollen vectors in species-rich communities.

Natural selection is thought to have shaped the evolution of floral scent; however, unlike other floral characters, we have a rudimentary knowledge of how phenotypic selection acts on scent. We found that floral scent was under stronger selection than corolla traits such as flower size and flower color in weakly scented Penstemon digitalis. Our results suggest that to understand evolution in floral phenotypes, including scent in floral selection, studies are crucial. For P. digitalis, linalool was the direct target of selection in the scent bouquet. Therefore, we determined the enantiomeric configuration of linalool because interacting insects may perceive the enantiomers differentially. We found that P. digitalis produces only (S)-(+)-linalool and, more interestingly, it is also taken up into the nectar. Because the nectar is scented and flavored with (S)-(+)-linalool, it may be an important cue for pollinators visiting P. digitalis flowers.

Weed species are ecological models that recently received considerable attention due to their particular strategies linked to their ruderal‐competitive traits. They are known to have the potential to provide additional floral resources for insects in flower‐poor agroecosystems. However, their floral traits are much more scarcely studied than those of plants found in other habitats, such as grasslands. The aim of this study was to describe the floral phenotype of weeds and to determine to what extent their floral traits match their ecological strategies as described based on leaf traits. We cultivated 19 forb weeds from perennial agroecosystems, previously identified in Mediterranean fields, in a greenhouse for seven months and collected data on 12 floral and five leaf traits. We tested whether these traits covaried and exhibited an ecological strategy at the phenotype scale. We found that in matters of flower production, weed species face a tradeoff: either numerous small, low‐stature flowers with small quantities of pollen and nectar, or few, large, higher‐held flowers with more pollen and nectar. The floral traits were found to reflect Grime's CSR strategies: the weed species producing fewer but costlier flowers belonged to C‐strategy species, whereas those producing more but less costly flowers belonged to species dominated by an R strategy. These findings indicate that the potential of weeds as floral resources for insects is related to their ecological strategies, which are known to be affected by agricultural practices that filter species composition. This implies that, as for the provision of other ecosystem services, weed communities can be managed to select species with floral traits matching the requirements of flower‐visiting insects like pollinators or parasitoid wasps. [ABSTRACT FROM AUTHOR]

Adaptations that attract pollinators to flowers are central to the reproductive success of insect‐pollinated plants, including crops. Understanding the influence of these non‐rewarding traits on pollinator preference is important for our future food security by maintaining sufficient crop pollination. We have identified substantial variation in flower shape, petal size, corolla‐tube length, petal spot size and floral volatile compounds among a panel of 30 genetically distinct lines of Vicia faba. Using this variation, we found that Bombus terrestris was able to distinguish between natural variation in petal spot size, floral volatile emissions and corolla‐tube length. Foragers showed some innate preference for spotted flowers over non‐spotted flowers and preferred shorter corolla‐tube lengths over longer tubes. Our results suggest that some floral traits may have significant potential to enhance pollinator attraction to V. faba crops, particularly if paired with optimised rewards. [ABSTRACT FROM AUTHOR]

Rose (Rosa spp.) is one of the most economically important ornamental species worldwide. Flower diameter, flower weight, and the number of petals and petaloids are key flower-size parameters and attractive targets for DNA-informed breeding. Pedigree-based analysis (PBA) using FlexQTL software was conducted using two sets of multi-parental diploid rose populations. Phenotypic data for flower diameter (Diam), flower weight (fresh (FWT)/dry (DWT)), number of petals (NP), and number of petaloids (PD) were collected over six environments (seasons) at two locations in Texas. The objectives of this study were to 1) identify new and/or validate previously reported QTL(s); 2) identify SNP haplotypes associated with QTL alleles (Q-/q-) of a trait and their sources; and 3) determine QTL genotypes for important rose breeding parents. Several new and previously reported QTLs for NP and Diam traits were identified. In addition, QTLs associated with flower weight and PD were identified for the first time. Two major QTLs with large effects were mapped for all traits. The first QTL was at the distal end of LG1 (60.44-60.95 Mbp) and was associated with Diam and DWT in the TX2WOB populations. The second QTL was consistently mapped in the middle region on LG3 (30.15-39.34 Mbp) and associated with NP, PD, and flower weight across two multi-parent populations (TX2WOB and TX2WSE). Haplotype results revealed a series of QTL alleles with differing effects at important loci for most traits. This work is distinct from previous studies by conducting co-factor analysis to account for the DOUBLE FLOWER locus while mapping QTL for NP. Sources of high-value (Q) alleles were identified, namely, 'Old Blush' and Rosa wichuraiana from J14-3 for Diam, while 'Violette' and PP-J14-3 were sources for other traits. In addition, the source of the low-value (q) alleles for Diam was 'Little Chief', and Rosa wichuraiana through J14-3 was the source for the remaining traits. Hence, our results can potentially inform parental/seedling selections as means to improve ornamental quality in roses and a step towards implementing DNA-informed techniques for use in rose breeding programs. [ABSTRACT FROM AUTHOR]

Flower traits, such as flower size or color changes, can act as honest signals indicating greater rewards such as nectar; however, nothing is known about shelter-rewarding systems. Large flowers of Royal irises offer overnight shelter as a reward to Eucera bees. A black patch might signal the entrance to the tunnel (shelter) and, together with the flower size, these might act as honest signals. We hypothesize that larger flowers and black patches indicate larger tunnels, and larger tunnels will increase pollinator visits, enhancing the plants' reproductive success. We measured seven species in a controlled environment and two species from three natural populations varying in flower size. Fruit and seed sets were assessed in these natural populations. We found a positive correlation between the flower, patch size, and tunnel volume, suggesting that the flowers and patch size act as honest signals, both under controlled conditions and in the wild. However, in natural populations, this positive relationship and its effect on fitness was population-specific. Flower size increased the fitness in YER I. petrana, and interactions between flower/patch size and tunnel size increased the fitness in YER and I. atropurpurea NET populations. This suggests that the honesty of the signal is positively selected in these two populations. This study supports the hypothesis that pollinator-mediated selection leads to the honest signaling of flower advertisement. [ABSTRACT FROM AUTHOR]

Sexual dimorphism is expressed as different morphologies between the sexes of a species. Dimorphism is pronounced in gynodioecious populations which consist of female and hermaphrodite individuals. The small size of female flowers in gynodioecious species is often explained by resource re‐allocation to seed production instead of large flowers. However, pollinator attraction is critical to female fitness, and factors other than resource savings are needed to explain the small size of female flowers. We hypothesized that the floral size dimorphism in the perennial gynodioecious Geranium sylvaticum (L.) is adaptive in terms of pollination. To test this "pollination hypothesis," we video recorded the small female and large hermaphrodite G. sylvaticum flowers. We parameterized floral visitor behavior when visiting a flower and calculated pollination probabilities by a floral visitor as the probability of touching anther and stigma with the same body part. Pollination probability differed in terms of flower sex and pollinator species. Bumblebees had the highest pollination probability. The small female flowers were more likely to receive pollen via several pollinator groups than the large hermaphrodite flowers. The pollen display of hermaphrodites matched poorly with the stigma display of hermaphrodites, but well with that of females. Although the small size of female flowers is commonly explained by resource re‐allocation, we show that sexual dimorphism in flower size may increase the main reproductive functions of the females and hermaphrodites. Dimorphism increases pollination probability in females and fathering probability of the hermaphrodites likely driving G. sylvaticum populations towards dioecy. [ABSTRACT FROM AUTHOR]

Altered precipitation patterns associated with anthropogenic climate change are expected to have many effects on plants and insect pollinators, but it is unknown if effects on pollination are mediated by changes in water availability. We tested the hypothesis that impacts of climate on plant-pollinator interactions operate through changes in water availability, and specifically that such effects occur through alteration of floral attractants. We manipulated water availability in two naturally occurring Mertensia ciliata (Boraginaceae) populations using water addition, water reduction and control plots and measured effects on vegetative and floral traits, pollinator visitation and seed set. While most floral trait values, including corolla size and nectar, increased linearly with increasing water availability, in this bumblebee-pollinated species, pollinator visitation peaked at intermediate water levels. Visitation also peaked at an intermediate corolla length, while its relationship to corolla width varied across sites. Seed set, however, increased linearly with water. These results demonstrate the potential for changes in water availability to impact plant-pollinator interactions through pollinator responses to differences in floral attractants, and that the effects of water on pollinator visitation can be nonlinear. Plant responses to changes in resource availability may be an important mechanism by which climate change will affect species interactions.

Plant pathogens evade basal defense systems and attack different organs and tissues of plants. Genetic engineering of plants with genes that confer resistance against pathogens is very effective in pathogen control. Conventional breeding for disease resistance in ornamental crops is difficult and lagging relative to that in non-ornamental crops due to an inadequate number of disease-resistant genes. Therefore, genetic engineering of these plants with defense-conferring genes is a practical approach. We used rice BSR2 encoding CYP78A15 for developing transgenic Torenia fournieri Lind. lines. The overexpression of BSR2 conferred resistance against two devastating fungal pathogens, Rhizoctonia solani and Botrytis cinerea. In addition, BSR2 overexpression resulted in enlarged flowers with enlarged floral organs. Histological observation of the petal cells suggested that the enlargement in the floral organs could be due to the elongation and expansion of the cells. Therefore, the overexpression of BSR2 confers broad-spectrum disease resistance and induces the production of enlarged flowers simultaneously. Therefore, this could be an effective strategy for developing ornamental crops that are disease-resistant and economically more valuable. [ABSTRACT FROM AUTHOR]

We exploited ecotypic variation in Impatiens capensis (Balsaminaceae) to test the hypothesis that mutation accumulation accompanying relaxed selection on the chasmogamous (CH) flower leads to more variable flower shapes and smaller flowers. Sun ecotype populations of this species occur along sunny riverbanks and marshes and produce both CH and cleistogamous (CL) flowers, while shade ecotype populations occur in shady forest floors and produce only CL flowers. In the shade ecotype, it is assumed that selection on the CH flower has been relaxed. Seedlings from population samples of the two ecotypes exhibited different first internode growth responses to low ratios of red:far-red light as seen in earlier studies of ecotypic differentiation to sunny versus shady conditions, helping to verify historical illumination conditions in the populations. We examined the CH floral mutation accumulation hypothesis by comparing the shape and size of the modified CH flower sepal under greenhouse conditions that triggered CH flowering in plants of both ecotypes. Contrary to our predictions, geometric morphometric analysis of sepal shape variation indicated little difference between the shade and sun ecotypes. We suggest that mutations that influence CH flower shape may have pleiotropic effects on structures or processes that remain under selection even when the CH flowers are not produced. On the other hand, sepal size was significantly smaller in the shade ecotype populations. In the case of CH sepal size, the mutational effects appear to be directional, towards producing smaller sepals, and would likely be deleterious if shade ecotype plants encounter sunnier conditions where the plants can produce CH flowers. [ABSTRACT FROM AUTHOR]

Geographic differences in floral traits may reflect geographic differences in effective pollinator assemblages. Independent local adaptation to pollinator assemblages in multiple regions would be expected to cause parallel floral trait evolution, although sufficient evidence for this is still lacking. Knowing the intraspecific evolutionary history of floral traits will reveal events that occur in the early stages of trait diversification. In this study, we investigated the relationship between flower spur length and pollinator size in 16 populations of Aquilegia buergeriana var. buergeriana distributed in four mountain regions in the Japanese Alps. We also examined the genetic relationship between yellow‐ and red‐flowered individuals, to see if color differences caused genetic differentiation by pollinator isolation. Genetic relationships among 16 populations were analyzed based on genome‐wide single‐nucleotide polymorphisms. Even among populations within the same mountain region, pollinator size varied widely, and the average spur length of A. buergeriana var. buergeriana in each population was strongly related to the average visitor size of that population. Genetic relatedness between populations was not related to the similarity of spur length between populations; rather, it was related to the geographic proximity of populations in each mountain region. Our results indicate that spur length in each population evolved independently of the population genetic structure but in parallel in response to local flower visitor size in different mountain regions. Further, yellow‐ and red‐flowered individuals of A. buergeriana var. buergeriana were not genetically differentiated. Unlike other Aquilegia species in Europe and America visited by hummingbirds and hawkmoths, the Japanese Aquilegia species is consistently visited by bumblebees. As a result, genetic isolation by flower color may not have occurred. [ABSTRACT FROM AUTHOR]

The present study evaluated the size of crocus flowers as an element of ornamental quality, depending on the biometric parameters of the plants, against the background of different growing substrates. Two types of crocus were studied: "Queen of the Blues" crocus and "Yellow" crocus. The plants were evaluated in terms of height (Ph, cm) at the beginning of flowering (Ph B-Flo) and at the end of flowering (Ph E-Flo). The size of the flowers (Fs) was evaluated based on the diameter (Fs, cm). Three different substrates were used: sand (V1), mixture of sand and compost (V2) and soil (V3). The bulbs were planted at t1 - mid-October (a), t2 - early November (b), and t3 - mid-November (c). There were 9 experimental variants: V1a - sand at t1; V2a - sand and compost at t1; V3a - soil at t1; V1b-sand at t2; V2b - sand and compost at t2; V3b - soil at t2; V1c - sand at t3; V2c - sand and compost at t3; V3c - soil at t3. The size of the flowers (Fs) varied between 3.97 cm (V1c) and 5.07 cm (V2a) in "Queen of the Blue", respectively between 3.83 cm (V1c) and 4.07 cm (V2b) in "Yellow" crocus. 3D models and in the form of isoquants graphically represented the variation of Fs depending on the physiological parameters (Ph B-Flo and Ph E-Flo). The fs estimation safety was quantified by evaluating the degree of fit between the true values (RFs) and the predicted values (PFs). PC1 explained 79.234% of variance, and PC2 explained 19.046% of variance in the case of the "Queen of the Blues" crocus, and in the case of Yellow crocus, PC1 explained 88.851% of variance, and PC2 explained 8.8951% of variance. [ABSTRACT FROM AUTHOR]

The study evaluated the vegetation and quality parameters associated with chrysanthemum flowers. Four cultivars of chrysanthemums were studied, cultivated in protected conditions: 'Yellow Snowdon', 'Tom Pearce', 'Palisade' si 'Avignon'. Shoots height (SH) and shoots number (SN) were evaluated as vegetative parameters that express the vegetation state of the plants; the determinations were made at the beginning of August - T1 and at the beginning of September - T2. Flowers diameter (FD) and flowering time (FT) were also evaluated as floral quality indices. The 'Yellow Snowdon' and 'Palisade' cultivars had high shoot height, with significant differences (LSD5%, LSD1%). Regarding the number of shoots, significant differences were registered for the cultivars 'Tom Pearce', 'Palisade', 'Avignon' (LSD5%, LSD1%). Flowers dimension (FD), as a quality parameter, showed significant differences for the cultivars 'Palisade' (LSD0.1%), 'Yellow Snowdon' and 'Tom Pearce' (LSD1%, LSD5%). Longer flowering time was recorded for the 'Avignon' cultivar (58 days) and shorter for the 'Yellow Snowdon' cultivar (52 days). The regression analysis facilitated the obtaining of some equations, as models that described the variation of FD and FT in relation to vegetative parameters (SH and SN), in statistical safety conditions (p <0.001). It was found that a number of 2.223 shoots (SN-T1), respectively 2.765 shoots (SN-T2), provided large flowers. The height of the shoots of 27.191 cm (SH-T1) and 91.816 cm (SH-T2) showed optimal values in relation to the flowering time (FT). [ABSTRACT FROM AUTHOR]

'Royal Gala' apple flower clusters usually have 5–6 flowers, each capable of producing a mature fruit at harvest. This study looked at the variation in dry weight among the flowers within spur clusters and also the variation in fruit quality at harvest where only one specific flower was retained to harvest. The king or terminal flower had the smallest pedicel dry weight and length (17.7 mm compared to a mean of 23.3 mm for the other flowers). Receptacle dry weight was largest with flowers 1 and 2 (27 mg compared to a mean of 26 mg for the other flowers). Receptacle dry weight of the king flower was poorly correlated with its diameter, but was highly correlated with the weight of the receptacle of the other flowers within the same cluster. Spur flower clusters were tagged at flowering and reduced to one flower per spur and followed through to harvest. Earlier opening flowers had an initial advantage in terms of fruit diameter on 20 November but fruit diameter at harvest was better correlated with diameter recorded on 16 December. Length/diameter ratio was significantly higher in fruit from king flowers (0.96 compared to a mean of 0.91 for the other flowers). Seed number and weight did not differ among the fruit from different flowers. There was far more variation in fruit quality and flower dry weight between clusters compared to variation within a cluster. [ABSTRACT FROM AUTHOR]

Species with rewardless flowers often have low fruit to flower ratios, although wide temporal and spatial variation in fruiting success can occur. We compared floral phenotypes, insect visitors and fruiting success in four populations of the small white (Cypripedium candidum) and yellow (C. parviflorum) lady's slipper orchids and their hybrids near the northern extent of North America's tall grass prairie.Flower and fruit numbers were observed for two seasons on marked individuals (n = 1811). Floral traits were measured on 82–140 individuals per taxon and analysed in relation to fruiting success. All insects found inside flowers were collected, inspected for pollen smears and measured for comparison to floral features.Among orchid taxa, C. candidum had the smallest flowers, lowest number and variety of insect visitors, and lowest fruit to flower ratios. These measures were intermediate in hybrids and highest in C. parviflorum, despite low flower numbers in the latter. Within orchid taxa, fruit number was positively related to flower number, but fruit to flower ratios decreased slightly, as would be expected if pollinators left unrewarding patches. Potential pollinators included the dipteran Odontomyia pubescens and hymenopterans Andrena spp., Apis mellifera and Lasioglossum zonulum.Cypripedium parviflorum had a reproductive advantage over C. candidum across multiple populations and years. Hybrids showed segregation for floral traits, and hybrid fruiting success increased with a deeper intensity of yellow pigment and larger escape routes for floral visitors. These same attributes likely contributed to the relatively high fruit set in C. parviflorum in the study region. Comparison of two rewardless slipper orchids (Cypripedium) and their segregating hybrids showed that pollinator activity increased with yellow pigmentation and larger exits from restrictive flowers, contributing to a ten‐fold difference in fruit set between the species. [ABSTRACT FROM AUTHOR]

The objective of the present study was to determine the effects of brassinosteroid application on the sex determination and floral growth of pomegranate flowers. Whole tress of Punica granatum 'Mayhoş-8' were sprayed with 0.001, 0.01, and 0.1 mg L-1 28-homobrassinolide (Hbr) at bud break. The selection of flowers was based on the appearance of a visible pistil/stigma and shape of the ovary of intact flowers. Grouping of bisexual flowers was based on their flower position, i.e., single, terminal, and lateral flowers, during the first flush of flowering in mid-June. Approximately 20 days and 40 days after spraying, 100 randomly chosen bisexual flowers per collection time were collected and measurements of floral parts were immediately taken. The differences between bisexual and functional male flowers were not distinct enough to assert any significant effects from the different Hbr treatments. Irrespective of treatments, the percentage of male flowers was higher than that of bisexual flowers. Hbr treatments applied at the bud break period had significant effects only on bisexual flowers that developed as single flowers. Applying 0.01 mg L-1 Hbr produced comparably lower percentages of single bisexual flowers (53.4%). Although the 0.1 and 0.001 mg L-1 Hbr treatments resulted in increased percentages of bisexual flowers, the difference was not significant. For the first collection time (mid-June), the effects of Hbr concentration on the size of the floral parts for bisexual flowers were only significant in ovary width and stigma diameter. As the concentration decreased, smaller ovaries were obtained. During the second flowering, application of 0.01 mg L-1 Hbr considerably increased the overall sizes of floral parts in bisexual flowers. Hbr might affect the ratio of flower formation in certain positions on a branch and could influence the growth of floral parts in bisexual flowers. Further elucidation of these effects would help to better understand floral organ development in plants. [ABSTRACT FROM AUTHOR]

Flower size and color variation are the main attributes in the floriculture industry that affect the consumers demand. Rosa gruss an teplitz and Rosa centifolia are the fragrant rose species known for their wonderful aesthetic beauty. However, they are limited in use due to their small sized flowers and no color variegation. In order to improve characters in rose species, shoot tips taken from micropropagated plants were incubated for three different periods of 5, 7 and 11 days in MS medium containing different levels (0,100, 150, 300 and 450 mg l-1) of colchicine. Rosa gruss an teplitz and Rosa centifolia yielded maximum plant height (15.12 and 17.23cm), number of nodes (4.80 and 6.93), internodal distance (3.15 and 2.48 cm), leaf area (5.26 and 10.50 cm2) and flower size (6.24 and 5.78cm) respectively at colchicine level of 450 mg l-1 with incubation period of 11days. Colchicine also induced variegation and variation in flowers of Rosa gruss an teplitz. Genetic variation was analyzed and dendrogram was developed to assess the relationship with parent material. The findings of this work add to the ongoing efforts to improve the characters through induction of mutation in rose flowers. [ABSTRACT FROM AUTHOR]

Alstroemeria presliana Herb. comprises two subspecies (A. presliana subsp. presliana and A. presliana subsp. australis), traditionally distinguished by the color and the size of the flower. The aim of this study was to evaluate, by objective methods, the taxonomic value of these characters to differentiate A. presliana subsp. presliana from A. presliana subsp. australis and to understand the nature of the within-populations variation observed in the field. Floral tepal color of Alstroemeria presliana was analyzed using CIE system (CIELab, CIELCh); tepal morphology was analyzed using multivariate methods. We worked with five Chilean populations of A. presliana subsp. australis collected in the Region of Araucanía (National Park Nahuelbuta, Angol) and 11 populations of A. presliana subsp. presliana from cordillera de los Andes in the Region of Biobío (Termas de Chillán, Los Pellines). For colorimetry, the outer, upper inner, and lower inner tepals were analyzed with a spectrophotometer colorimeter Hunterlab Colorquest. For morphometric analysis, tepals were digitized and analyzed using the software Zen 2011, and principal component analysis was applied to the morphological matrix. For outer and lower inner tepals, all CIELab coordinates were significantly different between the two subspecies. The two subspecies are distinguished by the b* (b* = 24.58 in subsp. australis vs. 11.23 in subsp. presliana), C* (C* = 30.01 in subsp. australis vs. 15.50 in subsp. presliana), and h° (h° = 1.00 in subsp. australis vs. 0.77 in subsp. presliana) coordinates of the upper inner tepals. Morphometric data were significantly different between subspecies. [ABSTRACT FROM AUTHOR]

Pollinator-mediated selection is a major evolutionary driver of floral traits; yet, such selection has rarely been tested for floral extreme traits. The Oncocyclus irises have exceptionally large, dark-colored flowers, associated with night-sheltering pollination and heat reward by the dark flowers., We quantified phenotypic selection on stem length, floral size and color in two species of iris ( Iris atropurpurea and I. haynei), using an experimental approach. We estimated selection gradients for both flowers open to natural pollination and for flowers receiving supplementary hand pollination, assuming that open-pollinated flowers are affected by all factors that could influence fitness, whereas supplementary pollination removes the possible influence of pollinators., We found evidence for pollinator-mediated selection to increase floral size and stem length in I. atropurpurea, but floral color in this species was not under pollinator-mediated selection. In I. haynei, no pollinator-mediated selection on any of the traits was detected., We conclude that the extreme floral size of I. atropurpurea has probably evolved as a result of pollinator behavior. Lack of such evidence for I. haynei and for the dark floral color in both species suggests that other non-pollinator agents are selecting for these prominent traits, or that phenotypic color variation in these irises is neutral. [ABSTRACT FROM AUTHOR]

Larger and longer lived flowers receive more pollinators, but may also involve increased water maintenance costs under hot, dry environments. Hence, smaller and/or short-lived flowers may buffer such costs. We surveyed floral longevity in three large-flowered MediterraneanCistusspecies. We hypothesize that: (1) inCistus, floral longevity decreases with increasing air temperature and flower size; (2) inC. ladanifer, flower size and longevity increase along an altitudinal gradient; (3) floral longevity is differentially affected by temperature rather than flower size along the gradient; (4) under similar temperature, floral longevity decreases with flower size. For each species, we evaluated the effects of flower size and air temperature on floral longevity. Specifically, floral longevity was surveyed along an altitudinal gradient in the largest flowered speciesCistusladanifer. Floral longevity inCistusspecies lasted < 1 d and was affected by air temperature, independently of flower size. InC. ladanifer, flower size increased along the gradient but floral longevity decreased. Still, floral longevity decreased with increasing air temperature and, to a lesser extent, with flower size. Together, our findings show a triangular relationship among air temperature, flower size and floral longevity with margins for plasticity to accommodate pollinator attraction with the costs of large-flowered Mediterranean plants. [ABSTRACT FROM AUTHOR]

Hummingbird flowers are typically red in color but the reasons for this are not well understood. Relatively few studies have examined hummingbird flower color preferences under natural conditions in which flower color varies within a species. We recorded hummingbird visitation rates to flowers that vary in color from yellow to red in a natural hybrid population between red- and yellow-flowered Mimulus aurantiacus subspecies. We also examined whether there were any correlations between color and flower size or nectar content. Finally, we reviewed the literature on hummingbird color choice tests using feeders and flowers. There were no correlations in this population between flower color and flower size, nectar volume, or sugar concentration. Nevertheless, hummingbirds undervisited the two most yellow color classes, overvisited orange flowers, and visited the two most red color classes in proportion to their frequency in the population. While Hummingbirds preferred flowers expressing red pigments to those that did not, the flowers with the most red hue were not the most attractive, as has been observed in similar studies with other species of Mimulus. While feeder studies generally fail to show hummingbird preference for red, all studies using flowers, including those that control all floral traits other than color, find consistent preference for red. Experiments are suggested that might help disentangle hypotheses for why hummingbirds exhibit this preference. [ABSTRACT FROM AUTHOR]

Premise of research. In flowers that are specialized, floral traits often differentiate in association with pollinator shifts. However, in species of generalized pollination, the role of pollinators in local population differentiation of floral traits is difficult to test. A crucial line of evidence is to contrast the direction and strength of pollinator selection among populations. Methodology. Variation in floral traits and pollinator assemblages was investigated in two populations of a generalist-pollinated herb, Trollius ranunculoides (Ranunculaceae), to detect the potential role of pollinators in floral differentiation. Pivotal results. The alpine population was visited more by flies, and the subalpine population was visited more by bees. Flower manipulations suggested that large flowers were more attractive to both bees and flies, while more petals were favored only by nectar-feeding flies. Compared to the subalpine population, plants in the alpine population had more petals per flower but smaller flowers where flies were predominant pollinators. Flower differences appeared to be genetically maintained in a common garden. Phenotypic selection analysis indicated stronger selection on petal number in the alpine population and oppositely more intense selection on flower diameter in the subalpine population, in accordance with the preferences of local pollinator assemblages. Conclusions. Heritability in floral traits, differences in local pollinator assemblages, and corresponding differences in phenotypic selection are together consistent with the view of pollinator-mediated selection on floral differentiation in T. ranunculoides. [ABSTRACT FROM AUTHOR]

Sedum perezdelarosae is proposed as a new species from the state of Puebla, Mexico. It belongs to section Pachysedum A. Berger because of its lateral inflorescence, thick leaves and yellow flowers. It seems to be closely related to S. batallae with which it shares its small size and densely aggregated habit. It differs from this species in the larger size of rosette and stem, leaf shape, inflorescences length and color of the corolla. [ABSTRACT FROM AUTHOR]

Floral traits used to attract and reward pollinators should become vestigial during the evolution of self-fertilization from outcrossing due to the reduced fitness benefits of investing in pollinator attraction. However, few traits have been studied, and covariation with outcrossing is rarely evaluated using genetic estimates of the mating system. We examined covariation between petal size and color and genetic estimates of outcrossing among populations of the yellow-flowered, bee-pollinated Camissoniopsis cheiranthifolia that exhibit striking variation in the mating system. We measured brightness, chroma, and hue, using a spectrophotometer, and petal size, using image analysis for flowers sampled in the field from 25 populations across the species' geographic range. Petals were brighter with higher chroma and lower hue (less red) in large-flowered populations than in small-flowered populations. Petal size, brightness, and chroma also correlated positively with the proportion of seeds outcrossed estimated from marker-gene analysis for a subsample of 11 populations. Parallel changes in petal size and color in selfing populations from two climatically different regions plus the maintenance of differences in flower size and color between large- and small-flowered populations when grown in a common glasshouse environment suggests genetic differentiation in these traits associated with mating system evolution. [ABSTRACT FROM AUTHOR]

Studies were carried out on seven taxa from beardless (Limniris) section: grassy leaved iris (Iris graminea L.), yellow iris (I. pseudacorus) and Siberian iris (I. sibirica L.), as well as hybrids from Sibiriceae section: I. 'Dreaming Yellow', I. 'Towanda Redflare', I. 'Violet Meer" and I. 'Wiltrud Gissel'. The following parameters were assessed: flower size, the length and width of stamens, the length of pistil, the color of: flower petals, pistil, stamen and pollen. It is considered that tetraploids have twice bigger flowers. The investigations confirmed this opinion. Iris 'Dreaming Yellow', which is tetraploid, has twice bigger individual elements of perianth than diploid taxons. Determining the sizes of individual elements of parental plants' perianth allowed to formulate a standard. It will serve for comparing morphological features of hybrids obtained in future. The identification of colour by means of Royal Horticultural Society Colour Chart occured not enough precise. [ABSTRACT FROM AUTHOR]

Although pollinators are thought to select on flower colour, few studies have experimentally decoupled effects of colour from correlated traits on pollinator visitation and pollen transfer. We combined selection analysis and phenotypic manipulations to measure the effect of petal colour on visitation and pollen export at two spatial scales in Wahlenbergia albomarginata. This species is representative of many New Zealand alpine herbs that have secondarily evolved white or pale flowers. The major pollinators, solitary bees, exerted phenotypic selection on flower size but not colour, quantified by bee vision. When presented with manipulated flowers, bees visited flowers painted blue to resemble a congener over white flowers in large, but not small, experimental arrays. Pollen export was higher for blue flowers in large arrays. Pollinator preference does not explain the pale colouration of W. albomarginata, as commonly hypothesized. Absence of bright blue could be driven instead by indirect selection of correlated characters. [ABSTRACT FROM AUTHOR]

Background and Aims Dimorphism among floral traits can evolve through variation in selection intensity between female and male performance, especially when sex functions are separated between flowers on a plant (monoecy), or between individuals (dioecy). In animal-pollinated species, male floral traits are predicted to be larger because competition for pollinators should favour larger displays. Floral dimorphism may be greater in dioecious than monoecious populations because of trade-offs between female and male function and opportunities for selfing in hermaphrodites. Methods These predictions were tested by surveying flower size, total flowers per inflorescence and daily display size in the insect-pollinated Sagittaria latifolia (Alismataceae). This species is useful for comparative analysis because populations are mostly either monoecious or dioecious. We examined floral dimorphism in 13 monoecious and 16 dioecious populations in eastern North America. Key Results Male flowers were significantly larger than female flowers in monoecious and dioecious populations, but there was no evidence for greater flower size dimorphism in dioecious populations despite their larger flower sizes overall. Although inflorescences in both dioecious and monoecious populations produced more male flowers, daily floral displays were significantly larger for female than male function due to more synchronous female flower opening. Daily floral display dimorphism was significantly greater in dioecious populations, due to greater female daily floral displays. There was a positive relationship between mean flower size and total flowers per inflorescence for both sexes in dioecious populations, but no relationship for either sex function in monoecious populations. Flower size dimorphism was positively correlated with the frequencies of females in dioecious populations. Conclusions The increased size and number of male flowers and protracted male floral displays in S. latifolia are probably shaped by sexual selection for more effective pollen dispersal. [ABSTRACT FROM PUBLISHER]

A new standard rose cultivar 'Snow Ball' was bred by the cross between the red standard cultivar 'Red Sandra' and the scarlet standard cultivar 'Baroness' at the National Institute of Horticultural and Herbal Science, in Suwon. The cross was made in 1998 and 'Snow Ball' was finally selected in 2003 after investigating the characteristics for three years from 2001 to 2003. 'Snow Ball', a white standard cultivar grows vigorously and has good flower shape. The major characteristics of this cultivar are 90.3 stems/m2/year in yield, 57.8 cm in length of cut flower, 6.1 cm in flower diameter, 85.7 in petal number, and 15.0 days in vase life. This cultivar can be propagated by both cutting and grafting. The consumer's preference of this cultivar is relatively higher than that of control cultivar, 'Tineke'. [ABSTRACT FROM AUTHOR]

A new standard rose cv. 'Honey Lemon' was bred by the cross between white standard cv. 'Escimo' and light pink standard cv. 'Medeo' at the National Institute of Horticultural Research Institute. The cross was made in 1999 and 'Honey Lemon' was finally selected in 2003 after investigating characteristics for three years from 2001 to 2003. 'Honey Lemon', a white standard cultivar grows vigorously and has good flower shape. The major characteristics of this cultivar are 248.0 stems/m2/year in yield, 53.0 cm in length of cut flower, 8.0 cm in flower diameter, 17.0 in petal number, and 16.9 days in vase life. This cultivar can be propagated by both cutting and grafting. The consumer's preference of this cultivar is relatively higher than that of control cv., 'Tineke'. (Registration number: 1151). [ABSTRACT FROM AUTHOR]

Abstract: Ion beam irradiation is attracting attention in floriculture as a means of inducing mutations. We investigated the effect of ion beam irradiation on induction of ray florets color/shape mutants from two strains of chrysanthemum to create new flower cultivars. The ray florets and leaf explants of chrysanthemum cultivars, ‘Shiroyamate’ and ‘H13’, respectively, cultured on MS medium were irradiated with 12C5+ ion beam at doses of 1, 2, 4 and 8Gy. The frequency of shoot primordia formation on ray florets explants of ‘Shiroyamate’ and shoot bud formation on leaf explants of ‘H13’ was decreased by 8Gy and 4Gy irradiation, respectively. The effective dose of ion beam was less than 4Gy in ‘Shiroyamate’ and less than 2Gy in ‘H13’. After exposure to an effective dose of ion beam, regenerated plants were grown in a green-house and the field. Yellow ray florets mutants from ‘Shiroyamate’, and various ray florets color mutants (dark-red, light red, pink, pink spray) and a flower shape mutant (double-ray florets) from ‘H13’ were induced by ion beam irradiation. Furthermore, a white mutant was obtained from a chimeric mutant. These results suggest that the combination of ion beam irradiation and tissue culture would be an effective means of generation mutants at a high efficiency. [Copyright &y& Elsevier]

Abstract: To study the morphological diversity of the popular ornamental crop Calibrachoa, traded since the 1990s, floral and vegetative characters of 91 commercial cultivars were compared to those of natural species. Floral colours were classified according to the ISCC-NBS system and the CIE LAB system. The numerical data obtained by measuring 19 floral and vegetative characters was tested with principal component (PC) analysis. Floral colour classes of commercial cultivars were divided into 37 groups according the ISCC-NBS system, whereas those of natural species were divided into 9 groups. These tendencies were readily observable in the scatter diagrams of the a* vs. b* values and the C* vs. L* values. As the result of PC analysis, six PCs were obtained. For PC4, which negatively correlated with the degree of nocturnal corolla limb closure, the majority of natural species showed negative scores whereas the majority of cultivars had positive PC4 scores. In terms of PC2 (flower size), PC3 (growth form), PC5 (floral shape) and PC6 (leaf shape), natural species were dispersed in a range wider than the cultivars. These results suggest that Calibrachoa cultivars possess more highly variable floral colour than natural species, and breeding programmes to diversify the floral colour seem to have progressed rapidly. The tendency of natural species to close the corolla limb toward evening has been removed almost completely from the cultivars. The floral size, growth form, floral shape and leaf shape of the cultivars were rather uniform compared to those of natural species. [Copyright &y& Elsevier]

Background and Aims: The phenotypic selection of a diverse insect assemblage was studied on a generalist plant species (Paeonia broteroi) in ten flowering seasons, with tests for whether visitor preferences for plants with larger flowers eventually translated into significant differences among plants in visitation rates, seed production, seed mass, seed germination and seedling survival. [ABSTRACT FROM PUBLISHER]

The article discusses a study by L. Fishman and J. H. Willis on pollen limitation and natural selection on floral characters in the yellow monkeyflower. Fishman and Willis applied a factorial design of pollen supplementation and pollinator exclusion to plants in an Oregon population of Mimulus guttatus and found that pollen supplementation increased seed production and pollinator exclusion reduced it. The findings imply that Mimulus guttaus plants with different pollinator abundances will be subject to strongly divergent types of selection. According to the study, in declining pollinator populations, the flowers themselves may begin to evolve to be less attractive and less reliant on pollinators, which might lead to declines.

Flowers exhibit tremendous variation in size (>1000-fold), ranging from less than a millimeter to nearly a meter in diameter. Numerous studies have established the importance of increased floral size in species that exhibit relatively normal-sized flowers, but few studies have examined the evolution of floral size increase in species with extremely large flowers or flower-like inflorescences (collectively termed blossoms). Our review of these record-breakers indicates that blossom gigantism has evolved multiple times, and suggests that the evolutionary forces operating in these species may differ from their ordinary-sized counterparts. Surprisingly, rather than being associated with large-bodied pollinators, gigantism appears to be most common in species with small-bodied beetle or carrion-fly pollinators. Such large blossoms may be adapted to these pollinators because they help to temporarily trap animals, better facilitate thermal regulation, and allow for the mimicry of large animal carcasses. Future phylogenetic tests of these hypotheses should be conducted to determine if the transition to such pollination systems correlates with significant changes in the mode and tempo of blossom size evolution. [Copyright &y& Elsevier]

Flowers are phenotypically integrated units that may require a precise configuration of floral organs for proper function. Plants, however, are metameric organisms that often exhibit architectural and temporal variation in floral size and shape. Clearly, architectural and temporal effects could interrupt phenotypic integration within flowers, yet such effects have not been explicitly examined. We compared correlations among floral characters for the closely related but morphologically divergent species Nicotiana alata and Nicotiana forgetiana and their artificial F3 hybrids. Principal components analysis of 16 floral traits identified two suites of correlated characters that are maintained in both taxa and in the hybrids, regardless of architectural and temporal variation in floral characters. We interpret the maintenance of these suites as evidence of common developmental regulation of correlated characters. One suite includes measures of corolla tube, gynoecium, and androecium length, while the other includes corolla limb and corolla tube aperture characters. The correlated suites of characters are tightly integrated, independent from characters of the other factor, and they participate in a common function. As such, these character suites represent phenotypic modules that have been maintained despite evolutionary changes in morphology during the divergence of the two species. [ABSTRACT FROM AUTHOR]

The structure of the plant inflorescence and flower is an important agronomic and ornamental trait studied for its potential economic applications. In particular, the capacity to modify flower size has always been a breeder’s goal. Genetic and molecular studies have shown that the Zea mays gene Ramosa1 ( Ra1) is involved in inflorescence branching regulation. In fact the ra1 loss of function mutation causes extra branching of the inflorescence. In this work we suggest a possible utilization of the Ramosa1 maize gene as a tool to modify inflorescence architecture and flower size in transgenic plants. In fact overexpression of this gene in Arabidopsis plants promotes an increase in reproductive organ size. Pollen, seeds, cotyledons, leaves and roots are also larger than those of the wild type. Analysis of organs from transformants showed that cell expansion was increased without apparently affecting cell division. These results suggest that the RA1 protein is able to up-regulate cell expansion in all organs of Arabidopsis plants. [ABSTRACT FROM AUTHOR]

Interspecific interactions can vary within and among populations and geographical locations, and this variation can influence the nature of the interaction (e.g. mutualistic versus antagonistic) and its evolutionary stability. Globeflowers are exclusively pollinated by flies whose larvae feed only on their seeds. Here we document geographical variability in costs and benefits in globeflowers in sustaining their pollinating flies throughout the range of this arctic-alpine European plant over several years. A total of 1,710 flower heads from 38 populations were analysed for their carpel, egg and seed contents. Individual and population analyses control for the confounding influences of variation in both: (1) population traits, such as fly density and egg distribution among flower heads; and (2) individuals traits, such as carpel and egg numbers per flower head. Despite considerable variation in ecological conditions and pollinator densities across populations, large proportions (range 33–58%) of seeds are released after predation, with a benefit-to-cost ratio of 3, indicating that the mutualism is stable over the whole globeflower geographical range. The stability of the mutualistic interaction relies on density-dependent competition among larvae co-developing in a flower head. This competition is revealed by a sharp decrease in the number of seeds eaten per larva with increasing larval number, and is intensified by non-uniform egg distribution among globeflowers within a population. Carpel number is highly variable across globeflowers (range 10–69), and flies lay more eggs in large flowers. Most plants within a population contribute to the rearing of pollinators, but some pay more than others. Large globeflowers lose more seed to pollinator larvae, but also release more seed than smaller plants. The apparent alignment of interests between fly and plant (positive relationship between numbers of seeds released and destroyed) is shown to hide a conflict of interest found when flower size is controlled for. [ABSTRACT FROM AUTHOR]

Two non-mutually exclusive hypotheses regarding the benefits of andromonoecy (producing perfect and female-sterile flowers on the same plant) are tested using Solanum carolinense. Results indicate that (1) staminate flowers are cheaper to produce than perfect flowers, even after correcting for their relative position in the inflorescence; (2) the resources saved by producing staminate flowers are not re-allocated to other fitness enhancing functions; and (3) the main morphological characteristic of staminate flowers, pistil reduction, does not increase either pollinator visitation or siring success of open-pollinated plants. These results indicate that neither the resource savings hypothesis nor the increased pollen donation hypothesis explains the evolution and maintenance of andromonoecy in S. carolinense. [ABSTRACT FROM AUTHOR]

1. Animal-pollinated plants influence their mating success through characteristics of their individual flowers and the arrangement of flowers into inflorescences. Previous studies of inflorescence function have focused on flower number, so the influences of traits of individual flowers on pollinator attraction and self-pollination between flowers remain unknown. 2. To investigate the effects of flower size and number on pollinator attraction and behaviour on inflorescences, we reduced the perianth size of flowers of Delphinium bicolor Nuttall and Delphinium glaucum S. Watson. 3. Reduction in flower size decreased the number of visits per inflorescence by bumble bees ( Bombus spp.), but increased the number of probes per visit. In contrast, both attraction and probes per visit increased in a decelerating manner with number of open flowers. The average number of probes per flower, which combines the effects of pollinator attraction and behaviour on inflorescences, did not differ significantly between small- and large-flowered plants, or with flower number. 4. The absence of significant variation among plants with different floral and inflorescence characteristics in visits per flower and nectar standing crop per flower indicate that bees achieved an ideal free distribution. 5. Our results suggest that large flowers reduce the incidence of geitonogamous pollination without reducing the frequency of probes per flower. [ABSTRACT FROM AUTHOR]

In many plants, including orchids, differential fruit set along the inflorescence has been attributed to pollinator behaviour. For instance, the pollinator, moving up the inflorescence, becomes satiated with the resources and leaves before visiting the upper flowers. Consequently, the pollinators do not visit flowers as frequently higher up the inflorescence. Alternatively, flower size may vary along the inflorescence, making pollination ineffective as flowers decrease in size. I tested for the presence of differential pollination along the inflorescence in a pollinator-limited tropical epiphyte, Lepanthes rupestris Stimson, and determined the likely cause of the observed pattern. As this species has inflorescences with sequential flowering, pollinator behaviour, moving up the inflorescence as in synchronous multiflowering inflorescences, can be discounted as an explanation for differential fruit set. Fruit set is shown to be more frequent at the base of the inflorescence, but male reproductive success through pollinarium removal is basically independent of flower position. Moreover, cross-pollination by hand at variable flower positions along the inflorescence results in equal fruit set, suggesting that resources are not limiting and cannot explain the cause of differential fruit production along the inflorescence in natural populations. Furthermore, flower size is shown to diminish along the inflorescence, suggesting that the pollinator(s) may be ineffective at depositing the pollinarium in the smaller higher flowers. Consequently, pollinator behaviour and its interaction with flower size, and not resource limitation, is likely to be the main cause of differential fruit set along the inflorescence in L. rupestris. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 151, 405–410. [ABSTRACT FROM AUTHOR]

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Gynodioecious populations (i.e. populations with female and hermaphrodite individuals) often contain a third phenotype with an intermediate sex expression. In Silene italica, this phenotype is characterized by a mixture of pistillate and perfect flowers and is thus gynomonoecious. To characterize sexual functions of these gynomonoecious individuals and their potential influence in the maintenance of gynodioecy, reproductive characters of the three sexual phenotypes were compared over 2 years in several families of S. italica produced by crossing. We found that gynomonoecious individuals were intermediate for flower production and female fertility characters, although they did not always significantly differ from female individuals. Perfect flowers of gynomonoecious and hermaphrodite plants were similar in size and pollen production. Gynomonoecious individuals were thus intermediate in female and in male functions. Family effects were found for most of the characters. The female advantage (i.e. the fertility of females compared to the female fertility of pollen producing plants) was not dramatically different when gynomonoecious plants were taken into account. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 583–591. [ABSTRACT FROM AUTHOR]

We looked at whether flower visitation rates, pollen limitation on seed production, and phenotypic selection on flower size through female function varied across a sharp gradient in light intensity (open meadow vs. forest) within a population of the perennial plant Campanula persicifolia L. (Campanulaceae). Flower visitation rates of putative pollinators were similar in both habitats. Seed number per fruit was strongly pollen limited, with no difference in the magnitude of pollen limitation between the two habitats. This strong pollen limitation set the basis for significant phenotypic selection, through female function, on a trait that probably is important for pollinator attraction: flower size. This was revealed by path analysis and structural equation modelling. The lack of difference in pollen limitation on seed production in the two habitats may be explained by the similarity in flower visitation rates in the two habitats. Moreover, the similarity in pollen limitation in the two habitats probably resulted in a similar magnitude and direction of selection on flower size through female function. Our results suggest that pollen limitation and selection through female function may vary little across space within a popualtion despite large variation in the environmental conditions experienced by plants. [ABSTRACT FROM AUTHOR]

• Background and Aims Flowers are relatively invariant organs within species, but quantitative variation often exists among conspecifics. These variations represent the raw material that natural selection can magnify, eventually resulting in morphological divergence and diversification. This paper investigates floral variability in Rosmarinus officinalis, a Mediterranean shrub. [ABSTRACT FROM PUBLISHER]